Despite your observation, formula like this is very intolerant of small errors and performance will be very much variable in practical situations.

Yes, an error of just a few hundreths of a gram of the phenidone will cause a substantial change. But an error of a gram of sulfite will make no perceivable difference, and I've verified robustness in the ascorbic acid. Further testing is needed to gauge sensitivity to type of water (if distilled/DI isn't used), temperature, dilution, and film-type.

And I forgot to mention this recommendation: Dissolve the sulfite first, so it'll scavenge the dissolved oxygen.

Originally Posted by RidingWaves

Great! Any idea what the conversion to Dimezone-S would be since I have that on hand...

I suggest 0.2 g of dimezone-S, because that's what XTOL uses. Others have changed this to 0.15 g of phenidone in XTOL-like formulae, so 0.2 g dimezone-s should be very close.